cifs: change bleft in decode_unicode_ssetup back to signed type

BugLink: http://bugs.launchpad.net/bugs/788691

commit bfacf2225a955bea9c41c707fc72ba16009674a0 upstream.

The buffer length checks in this function depend on this value being a
signed data type, but 690c522fa converted it to an unsigned type.

Also, eliminate a problem with the null termination check in the same
function. cifs_strndup_from_ucs handles that situation correctly
already, and the existing check could potentially lead to a buffer
overrun since it increments bleft without checking to see whether it
falls off the end of the buffer.

Reported-and-Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Steve Conklin <sconklin@canonical.com>

diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
index 1676570..7e2dc59 100644 (file)
--- a/fs/cifs/sess.c
+++ b/fs/cifs/sess.c
@@ -277,7 +277,7 @@ static void ascii_ssetup_strings(char **pbcc_area, struct cifsSesInfo *ses,
 }
 
 static void
-decode_unicode_ssetup(char **pbcc_area, __u16 bleft, struct cifsSesInfo *ses,
+decode_unicode_ssetup(char **pbcc_area, int bleft, struct cifsSesInfo *ses,
                      const struct nls_table *nls_cp)
 {
        int len;
@@ -285,19 +285,6 @@ decode_unicode_ssetup(char **pbcc_area, __u16 bleft, struct cifsSesInfo *ses,
 
        cFYI(1, "bleft %d", bleft);
 
-       /*
-        * Windows servers do not always double null terminate their final
-        * Unicode string. Check to see if there are an uneven number of bytes
-        * left. If so, then add an extra NULL pad byte to the end of the
-        * response.
-        *
-        * See section 2.7.2 in "Implementing CIFS" for details
-        */
-       if (bleft % 2) {
-               data[bleft] = 0;
-               ++bleft;
-       }
-
        kfree(ses->serverOS);
        ses->serverOS = cifs_strndup_from_ucs(data, bleft, true, nls_cp);
        cFYI(1, "serverOS=%s", ses->serverOS);